Thread: Adventures with libpcap

Hey, I am trying to do some programming using the pcap library on my FreeBSD box. I am using the tutorial here ( Programming with pcap ) as a guiideline. I have hit a few snags along the way but was able to correct them. However there is one error that I seem unable to work out. I can compile the following code fine, but when I fun it I keep getting the error

Code:

Couldn't install filter host any:BIOCSETF: Bad file descriptor
pcap_setfilter: BIOCSETF: Bad file descriptor

Here is my code:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <pcap.h>
#include <pcap/pcap.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <net/bpf.h>


int main(int argc, char *argv[])
{
    char errbuf[PCAP_ERRBUF_SIZE], *dev;
    char filter_exp[] = "host any";
    pcap_t *handle;
    int ret = 0;
    struct bpf_program *bpf_ptr;
    bpf_u_int32 mask;        /* The netmask of our sniffing device */
    bpf_u_int32 net;        /* The IP of our sniffing device */
    struct pcap_pkthdr header;    /* The header that pcap gives us */
    const u_char *packet;        /* The actual packet */


    dev = argv[1];


    if (pcap_lookupnet(dev, &net, &mask, errbuf) == -1) {
        fprintf(stderr, "Can't get netmask for device %s\n", dev);
        net = 0;
        mask = 0;
    }


    handle = pcap_open_live(dev, BUFSIZ, 1, 0, errbuf);
    if(handle == NULL){
        fprintf(stderr, "pcap error %s", errbuf);
        exit(1);
    }
    ret = pcap_compile(handle, bpf_ptr, filter_exp, 1, (bpf_u_int32) 0);
    if(ret == -1){
        pcap_perror(handle, "pcap_compile");
        exit(1);
    }
    ret = pcap_setfilter(handle, bpf_ptr);
     if(ret == -1){
         fprintf(stderr, "Couldn't install filter %s:\n%s\n", filter_exp, pcap_geterr(handle));
         pcap_perror(handle, "pcap_setfilter");
         return(2);
     }
     /* Grab a packet */
        packet = pcap_next(handle, &header);
        if(packet == NULL){
            pcap_perror(handle, "pcap_next");
        }
        /* Print its length */
        printf("Jacked a packet with length of [%d]\n", header.len);
        /* And close the session */
        pcap_close(handle);
        return(0);


}

Obviously it is an error in which I have a bad file descriptor, but I don't know where to go from there. Thank you in advance.